Dimensions US-China-South Africa: Establishing genetic, phylogenetic and functional mechanisms that shape microbiome diversity of polar and alpine soils

Microorganisms are the foundations of ecosystems and drive the biology and chemistry in soils, e.g. the conversion of soil organic matter into the greenhouse gases carbon dioxide and methane, as well as nitrogen and phosphorous compounds that can be used by plants. Soil microbial community diversity maintains ecosystem stability and sustainability. Understanding the ecology of these microorganisms is one of the most compelling scientific challenges. This project will focus on the microbial ecology of soil ecosystems in the Arctic, Antarctic, and Tibetan Plateau. These 'tri-polar' soils are chosen for study as they are disproportionately impacted by climate change and predicted to show increased microbial activity and enhanced turnover of soil organic matter in the future. While microbes excel at adapting to environmental change, the functional implications of microbial community transitions remain to be characterized. Laboratory- and field-based approaches will identify microorganisms that are successful in these 'tri-polar' soil ecosystems and why, i.e., which bacterial species/strains are successful and what functional traits make them successful. Understanding how soil ecosystems respond in these polar regions is critical for evaluating the controls of biogeochemical cycling and clarifying microbial feedbacks in a changing world. This project will assemble an international team and recruit young scholars to reflect a blend of expertise in microbiology, ecology and environmental sciences. Research will be integrated with educational activities by involving samples and data into hands-on classroom training at the K-12, undergraduate, and graduate levels.

This project will delineate mechanisms that lead to diverse soil microbial communities that are hallmarks of stable and sustainable soils. We lack predictive understanding of mechanisms that regulate and maintain microbial biodiversity and how this relates to biogeochemically relevant microbial functions. Integrative approaches are needed to identify the principles that shape and maintain this biodiversity. This project combines genetic, phylogenetic, and functional dimensions of biodiversity to probe factors that shape the 'morass of diversity' of soil systems. The overarching hypothesis is that resource partitioning, selective predation, and temporal separation of activity each contribute to the success of particular bacterial strains/species in polar and alpine systems. The international research team will focus on testing these hypotheses in soils across Arctic, Antarctic and Tibetan Plateau habitats with the Acidobacteria as a model microbial phylum for study. Laboratory- and field-based approaches will be linked to describe the genetic, phylogenetic and functional diversity the Acidobacteria, one of the most ubiquitous but elusive bacterial phyla found in terrestrial ecosystems around the globe. The study will identify their ecosystem functions in soils, their interactions with other microbes, their adaptations to environmental stress such as climate change, and will assess their in situ dynamics and activity. Integration of these data will address which organisms compete for resources, avoid predation, and ultimately, occupy fundamentally distinct niches in these ecosystems. Elucidating these equalizing/stabilizing mechanisms can begin to explain the tremendous bacterial diversity observed in soil microbiomes.

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.